Abstract
We have performed Mössbauer studies on several oxy-heme model compounds, and for two of them we also have derived the threedimensional structure from X-ray studies; I: [Fe(O2) (SC6HF4) TPpivP] [Na⊂18C6] and II: [Fe(O2) (SC6HF4)TPpivP] [K⊂222]. Compound I shows a pronounced temperature-dependence of ΔEQ, i. e. 2.17 mms-1 at 4.2 K and 1.55 mms-1 at 295 K, while ΔEQ of compound II is practically temperature-independent, i.e. ca. 2.05 mms-1. The X-ray structure analysis of these model compounds provides us with the fact that O2 occupies three different sites in I and only two sites in II. From the experimentally known occupancies of these sites at specific temperatures we were able to apply relaxation calculations for the electric field gradient tensors in I and II, and we found for both compounds that our calculated ΔEQ(T)-data are in agreement with our experimental results. These findings imply that the dynamic jump behavior of O2 among the different sites in oxy-heme model compounds is responsible for the temperature-dependence (like in HbO2) or temperature-independence of ΔEQ (like in cytochrome P450).
Original language | English |
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Journal | Hyperfine Interactions |
Volume | 29 |
Issue number | 1-4 |
Pages (from-to) | 1411-1414 |
Number of pages | 4 |
ISSN | 0304-3843 |
DOIs | |
Publication status | Published - 01.02.1986 |